JPS593733B2 - Ichigun reflex camera no. - Google Patents

Description

[Detailed Description of the Invention] 0 The present invention divides a subject image into upper, lower, left, right, etc. parts using two model prisms, and ensures that the divided images coincide at the dividing boundary plane when the images are brought into focus. The present invention relates to an improvement in a focus detection device that performs focus detection using the present invention.

The present invention performs focus detection based on the principle that when a subject image divided into 5 parts vertically or horizontally by a model prism is brought into focus, the images coincide at the dividing boundary surface, and the same photoelectric conversion element group It is an object of the present invention to provide a focus 00 point detection device for a single-lens reflex camera that performs focus detection with higher precision by using different focus detection methods together by switching the wiring. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of the optical system of a single-lens reflex camera, showing a state in which it has a focus detection device according to the present invention.

In the figure, 1 and 1' are the subject, 2 is the lens group that makes up the photographic optical system, 3 is a total reflection mirror with a half mirror 3' in the center, and 4 is attached to the center of the back surface of the total reflection mirror 3. Total reflection mirror, 5 is focusing plate, 6 is condenser lens, T is pen prism, 8 is eyepiece, 9
is the eye of the photographer, etc. 10 is film, 11, 11'
12 is a center line (hereinafter referred to as the horizontal center line) indicating a position optically equivalent to the film 10, and 13 is the image of the subject 1, ``5'' photoelectric conversion. Lenses for forming an image on the element group 14, dl, d
2...dn, dl', d2'...
. . . dn' is a minute photoelectric conversion element constituting the photoelectric conversion element group 14, and 15 is a focus detection device that processes the output of the photoelectric conversion element group 14 and performs focus detection, details of which will be described later.

FIG. 2 is a detailed diagram of the photoelectric converter group 14, with the horizontal center line 1
2 as the boundary, D of the microphotoelectric conversion element, and Dl7, d2
and D2', .

FIG. 3 shows the relationship between two wedge-shaped prisms 11, 111 tilted in opposite directions and the photoelectric conversion element group 14,
A shows the subject image on the photoelectric conversion element group 14 when the focus is not matched and when the mouth is closed. Furthermore, 16,
161 indicates a subject image, and subject 1 and V refer to 1 and 1.
6, V and 16' correspond. Furthermore, Figures 1 to 3
The relationship between the optical system of the single-lens reflex camera shown in the figure and the photoelectric conversion element group will be briefly described.

Subject images 1 and 1! are captured by the lens group 2 that constitutes the photographic optical system. is the half mirror 37 at the center of the total reflection mirror 3
is reflected by the total reflection mirror 4, and an image is formed in the vicinity of two wedge-shaped prisms 11 and 1' tilted in opposite directions and having a horizontal center line 12 located at an optically equivalent position to the film 10. Tie. The image is divided into two by the two wedge-shaped prisms 11 and 117 tilted in opposite directions, and each is imaged onto a pair of photoelectric conversion element groups 14 by the imaging lens 13. As shown in FIG. 2, the photoelectric conversion element group 14 and the horizontal center line 12 optically coincide with the center of the paired microphotoelectric conversion elements.

Therefore, by moving the lens group 2 constituting the photographing optical system in the direction of the arrow, the subject images 1 and 17 formed by the photographing lens group 2 are focused on the horizontal center line 12 in FIG. 1, as shown in FIG. 3A. When no image is formed, the movement of the two wedge-shaped prisms 11, 11' tilted in opposite directions and the imaging lens 13 causes the horizontal center line (paired photoelectric converters) to appear on the photoelectric conversion element group 14. It coincides with the center line of the conversion element group 14.

)12 as a boundary and the image is formed with a shift. Note that when an image is formed on the horizontal center line 12 in FIG. 1, an image that coincides with the horizontal center line 12 as a boundary is formed on the photoelectric conversion element group 14 as shown in the opening in FIG.

Next, before explaining the gist of the focus detection device according to the present invention, the force formula for electrically detecting the optically divided image and detecting the focus will be explained as shown in FIGS. 4 and 7. . FIG. 4 is a wiring diagram of the photoelectric conversion element 14 used in the focus detection power type, and each minute photoelectric conversion element d1 to Dn of the photoelectric conversion element 14 is
, dl' to Dn7 are sufficiently small in the direction perpendicular to the horizontal center line 12, the subject images 16, 1 as shown in the opening of FIG.
6' coincide with each other with the horizontal center line 12 as a boundary, it can be considered that the same amount of light is incident on each pair of minute photoelectric conversion elements.

In such a configuration, as shown in FIG. 4, the anode of the minute photoelectric conversion element d1 and the cathode of Dl7, D
2 anode and D2' cathode,...
If the anode of Dn and the cathode of Dnl are wired in parallel in opposite directions, each terminal 1, 2, 3, etc.
... between n and common terminal C, there are output differences between minute photoelectric conversion elements 11-1, 712-12', I3-13'
,...In-1n! is obtained. Therefore, in the case of FIG.
There is a difference in output between the m7 section and the m7 section. (However, 1≦K, m×n
In addition, except for the subject image, the illuminance in the vicinity of the horizontal center line 12 is assumed to be equal. ) In this case, if ε is the sum of the absolute values of the outputs of the anode terminals 1, 2, . . . n in FIG. In addition, when the subject images 16, 16' are formed on the horizontal center line 12 in FIG. 1 as shown in the opening of FIG. Since the output difference between the minute photoelectric conversion elements Ds and Ds7 corresponding to the photoelectric conversion elements 16 and 16' is O, the above value is accordingly, and the output ε becomes the minimum value 0 at the time of focusing.

FIG. 5 is a wiring diagram of a photoelectric conversion element 14 used in a focus detection method different from that shown in FIG. 1
'Tsu 2! 41t6'9*''''3603n-1' and the common common terminal C7 are connected in parallel in opposite directions, and the output difference between each microphotoelectric conversion element is determined by 11. ．．
．． ．．
．． ．． '112913
-14!゜゜゜゜゜゜゜゜゛1n-2-1n-1) 1
2-I3', I4'-15', ......In
-1''-1n! is obtained between each terminal and the common common terminal C!.

(The number of elements is set to an odd number in FIG. 7.) Therefore, in FIG. is clearer than the state in A, so the minute photoelectric conversion element Dnl in A is
-1~Dm or Drn-Dnl+1 or Dk-/~Dk
Or, the output difference between adjacent elements between Dk' and Dk+17 is 1 m1''ImiimP'Im+D'Ik-
1 ~Ik7,ik! 〜Ik+1′, Ds−1〜D in the mouth, or D8〜D8+1 or D8−1(〜D
Output difference between adjacent elements between 8', D8' and D8+, 7 1s-RisP'Is+1yis-1!518!
,I8! ~The force of I8+17 is large, and when the sum of the absolute values of the outputs is taken as the sum of the outputs for a general image, the value when the element arrangement follows FIG. 5 shows the maximum value when in focus. become.

Of course, only one side of the photoelectric conversion element group 14 may be used, and it goes without saying that the absolute value is raised to the power of p, and the larger p is, the sharper the area near the time of focusing becomes.

FIG. 6 shows a focus detection device for a single-lens reflex camera according to the present invention, in which the detection power formula shown in FIG.
This can be used in combination with the detection method shown in the figure.

The switch groups 27, 28, and 29 are mounted so that all the switches are connected to the contacts A side or B side, and when connected to the A side, the switches shown in FIG. A power formula is used.

That is, by connecting the switch groups 27 and 28 to the A side, the difference between the outputs of the paired microphotoelectric conversion elements is input in parallel to the parallel input serial output conversion circuit 17, and the outputs are input to I,
〜Il7, i2〜I2′ ......In-1
n! are input to the absolute value circuit 18 on the A side of the switch 29 in this order.

As a result, the absolute value circuit 18 111-1171,
1i2-12'1, 11n-1n7
Outputs are generated in the order of 1, and are sequentially input to the adder circuit 19,
The output yields n Σ 1iq-1q'l.

q=1 This output is inverted and shifted up by the circuit 22.
- Obtain Σ 1iq-1q1I>0 and temporarily store it in the q=1 storage circuit 23.

The operation of this circuit 22 will be described below.

The operation of the inversion and shift-up circuit 22 is as shown in FIG.

(>0) This is a circuit that also shifts up and converts the minimum value (indicated by line b) to the maximum value. At the same time that the output is stored in the temporary storage circuit 23, each switch is connected to the A side. When connected to the A side, the detection method shown in FIG. 5 is used. That is, by connecting the switch groups 27 and 28 to the A side, the output difference between adjacent microphotoelectric conversion elements (FIG. 6 shows a configuration using one element group) can be adjusted to the parallel input. The input is input to the serial output conversion circuit 17, and the switch 29 causes the A side absolute value circuit 18, exponentiation circuit 24, adder circuit 19, etc. to output Ni2ll2, -.
1-12, 1P is obtained.

(However, q=1p is a constant determined by the exponentiation circuit 24 and is 1
, 2, . . . 0) which indicates the value of
5 and input it to the maximum value detection circuit 26 to obtain the maximum value.

Of course, when the maximum value is reached, that is, when the focus is met, the light emitting element 21 such as a light emitting diode is activated to notify the photographer when the focus is met, but it is also natural that the output can be used to apply to automatic focus detection. . Naturally, when p is i, the exponentiation circuit 24 is not necessary, and when p is an even number, the absolute value circuit 18 is not necessary.

Of course, the absolute value circuit, the adder circuit, etc. may be shared. In Fig. 7, b is the output of the temporary memory circuit 23, and c is the addition circuit 19 on the A side when the switch is connected to the A side.
and d indicate the output of the multiplier circuit 25. As is clear from the figure, the combined use of the two focus detection force formulas sharpens the output near the focal point, improving detection accuracy.

In this way, according to the present focus detection device, mechanisms for detecting the in-focus state using different focus detection power formulas are used together, and one microphotoelectric conversion element group is switched in synchronization with the switching of the mechanisms. By switching the wiring, it is now possible to perform focus detection by using focus detection methods based on different principles, making it possible to perform focus detection with higher precision, smaller and simpler equipment, and the effect is Extremely large.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of the optical system of a single-lens reflex camera showing an embodiment of the present invention, Fig. 2 is a layout diagram of a group of photoelectric conversion elements, and A in Fig. 3 is a diagram of a group of photoelectric conversion elements when the pits are shifted. Figure 3 shows the image of the subject on the photoelectric conversion element group when the pits match, Figure 4 shows the wiring diagram of the micro photoelectric conversion element, and Figure 5 shows the wiring diagram of the micro photoelectric conversion element. 6 is a block diagram of the focus detection processing device, and FIG. 7A is a diagram showing the relationship between the amount of defocus and the focus detection output. 1, ``...Subject image, 2... Lens group constituting the photographing optical system, 3... Total reflection mirror,
3! -...Half mirror, 4...Total reflection mirror, 5...Focal plate, 6...Condenser lens, 7...Penta prism, 8...
...Eyepiece, 9...Eye of the photographer, etc., 1
0...Film, 11, 11! -...Wedge-shaped prism, 12...Horizontal center line, 13...
...Luns, 14...Photoelectric conversion element group, d1~
Dn, d/~Dnζ...Minute photoelectric conversion element, 15
...Focus detection processing device, 16, 16...
・Subject image.

Claims (1)

[Claims] 1 The central part of the flip-up total reflection mirror of a single-lens reflex camera on the optical axis is a half mirror, and a small total reflection mirror that bends and reflects the imaged light passing through it to the bottom is attached behind the jump mirror. Two wedge-shaped prisms that are tilted to reflect each other in the horizontal direction are placed on a plane equivalent to the film plane on the optical axis, and behind them are an imaging lens and a boundary line that optically coincides with the horizontal center line of the wedge-shaped prisms. In a single-lens reflex camera in which a group of micro photoelectric conversion elements are arranged in parallel on both sides in a pair with the micro photoelectric conversion element group in between, the sum of the absolute values of the relative output differences between opposing elements of the micro photoelectric conversion element group is detected and the extreme value is determined. (2n-1) power of the absolute value of the difference in output proportional to the amount of incident light between the means for detecting focus and one or both adjacent elements of the microphotoelectric conversion element group (where n=1, 2, 3...
) or the 2n power of the output difference (where n=1, 2, 3...
. . . ), and a means for detecting focus based on the maximum value, and in accordance with the switching of the two detection means, the wiring of the pair of microphotoelectric conversion element groups is switched. A focus detection device for a single-lens reflex camera, characterized in that focus detection is performed using different focus detection methods in one microphotoelectric conversion element group.